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From: bw@hpcvlx.cv.hp.com (Bill Wilhelmi)
Newsgroups: comp.music
Subject: Re: Frequency shifting
Message-ID: <110260001@hpcvlx.cv.hp.com>
Date: 23 Jul 90 18:46:00 GMT
References: <3956@rodan.acs.syr.edu>
Organization: Interstate 5
Lines: 37

/ hpcvlx:comp.music / davisonj@ecn.purdue.edu (John M Davison) /  7:53 am  Jul 20, 1990 /

 >	In the interest of accurate, consistent terminology, I am
 >compelled to point out that frequency shifting and pitch shifting are
 >two very different things; let's keep it that way.
 >
 >Pitch shifting = frequency scaling
 >freq(new) = freq(old) * factor
 >
 >Frequency shifting:
 >freq(new) = freq(old) + factor
 >
 >-davisonj@en.ecn.purdue.edu
 >----------

Being on the fringe of this sort of stuff, I can't help but notice an
oddity.  If factor = (2 * freq(old)), then

   freq(new) = freq(old) + factor    [ Freq Shift ]
	     = freq(old) + 2 * freq(old)
             = freq(old) * 3         [ Pitch Shift ]


For Pitch Shifting and Frequency Shifting to have any differentiation of
meaning, severe constraints must be placed "factor".   The point is that
according to the definition above, the value of "factor" doesn't seem
to give enough information about whether the shift is a Pitch or Frequency
shift.  The only difference seems to be that pitch shifts are large-scale
frequency shifts.  But they still both modify the frequency.  Am I missing
some big point?


Bill Wilhelmi    
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